Ive never used or considered an inflatible board. I travel with a 65L board, 2-3 foils and 2-4 wings (depending on duration and conditions). I can sometimes get by with a single large board bag if I pack light, but I find I'm better off without overpacking the board bag (limit to the board, foils and maybe a wing), and just packing another large duffel with wings, pump, tools etc....
If you are dealing with weight limits, remember that wing bags, foil hardware, foil cases add up. You can often forgo the bags, double up the wings in a single bag, or buy minimal lightweight bags to lighten things up. Obvious, but study forecasts in advance and travel with an efficient foil and wing quiver for the conditions (don't bring everything).
If you wind up traveling with a hard board do yourself a favor and buy a Flexi Hex wrapper. I travel with my board a lot and I would get dings every time. Since I started using this, Ive had no issues. It only lasts for a trip (maybe two if you are lucky) but it is lightweight, cheap and works for protection. I have no affiliation with the company - its just been a really convenient product for me and I'm glad I found it.
www.surfdome.us/Flexi-Hex-Lite-Single-Sleeve-Surf-Accessory/sd50156387.htm?colour=Brown&sku=863719&productid=234561&gclid=Cj0KCQiA4aacBhCUARIsAI55maHaGtK2aLNxPRby7TsFo4eNYpHNIwDzy8kkHeYoLm73ixelqruVqdEaAgBVEALw_wcB